Davy Villanueva hoped the fish would be biting when he went out to the San Antonio River a few weeks ago, but he never imagined he'd see a tooth bigger than the size of his two fists.

The Karnes City, Texas, fisherman found what he believes is a tooth from a mastodon, the big-tusked behemoths that roamed North America as far back as 3.75 million years ago, according to Illinois State Museums. The mammoth-related beasts became extinct 11,000 years ago.

Villanueva told KENS 5 TV in San Antonio that the recent drought had lowered river levels so much that he found the tooth in about a foot of water.

“I walked in the river and reached down in there and pulled it out, and wow, I have never seen anything like this,” Villanueva told the local station.

Villanueva won't reveal exactly where he found the pronged tooth -- not even to his wife, Patty Cruz. He thinks there may be more remains at the spot, but recent rains have raised water levels too high to explore further.

"It's certainly a mastodon tooth--lower molar, probably a young animal because it's apparently unworn, or little worn," Dr. Ross MacPhee, a mammologist at the American Museum of Natural History, told The Huffington Post in an e-mail after seeing video of Villanueva's discovery. "Finds are often made along watercourses like old river beds and lake margins. Mastodons seem to have preferred lacustrine and riparian habitats."

Mastodon teeth are considered collectibles and can be bought on eBay. Villanueva said he's been offered $500 for his mighty molars but turned it down. He said he might donate the seven-pointed tooth to a museum or college.

He's also thinking of giving the tooth to his 7-year-old son but told KENS 5, “He’s scared of it. He says, 'Papo, go put it back in the water because it keeps raining.' "